If the microwave turntable doesn't turn the turntable motor might be worn out. This is a common problem and relatively easy to replace.

Touchpad and Control Panel

If the microwave turntable doesn't turn the touchpad and control panel might be defective. This is not common. Test the turntable motor first.

Touchpad

If the microwave turntable doesn't turn and the touchpad has a button to turn the turntable on and off the touchpad might be defective. Check the turntable motor first, that is more likely.

User Control and Display Board

If the microwave turntable doesn't turn the turntable motor might be worn out. This is a common problem and relatively easy to replace. If the motor is good, the user control and display board may be defective.